<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      li {
        width: 200px;
        border: 1px dashed #000;
        background-color: #cecece;
      }
    </style>
  </head>
  <body>
    <input type="button" value="more" />
    <ul>
      <li>1</li>
      <li>2</li>
      <li>3</li>
      <li>4</li>
      <li>5</li>
    </ul>
  </body>
  <script>
    var oBtn = document.querySelector("input");
    var oUl = document.querySelector("ul");
    var aLi = document.querySelectorAll("li");
    oBtn.addEventListener("click", function () {
      for (let i = 0; i < aLi.length; i++) {
        var Li = document.createElement("li");
        oUl.appendChild(Li);
      }
    });
    oUl.addEventListener("click", function (ev) {
      //   console.log(ev.target);
      //   console.log(ev.target.tagName);
      if (ev.target.tagName == "LI") {
        console.log("niubilitity");
      }
    });
  </script>
</html>
